Firstly, do not bother with the free version unless you are a very small blogger who has very few followers...if you are a business then just pay the fee for the pro version if you really want a basic live chat utility. The following comments are based on very limited real testing:

PROs:
- Great value for a basic chat utility

CONS/IMPROVEMENTS REQUIRED
- The customer/visitor instigating the chat call can be left wondering whether anyone is attending to them. I use chat contact regularly with my ISPs and they display a "so-and-so it typing" message you when the person at the other end is preparing a chat reply. Without this a customer is in the dark and feeling ignored or imagines the connection has crashed or whatever.
- The is no facility for the customer to end the chat (other than clicking the 'close' cross). If the option is chosen by the operator to set a 24 hour period with no chat pop-ups (when a customer clicks the cross) the customer has no way to start a new chat.
- There is no option for the customer to collapse the chat box at the end of a session (unless they click the cross - see above).
- There is no option for the customer to have a transcript of the chat emailed to them

All in all - pretty good but not 'business-ready' even for a small business like mine.